Cement admixtures and the like, in which such waste products are used as raw materials, have been developed in recent years with a view to efficiently using industrial waste and/or ordinary waste. Such conventional cement admixtures may comprise blends of 10 to 100 parts by weight of gypsum (anhydrous basis) and 5 to 50 parts by weight of calcium carbonate relative to 100 parts by weight of blast-furnace slag powder, specifically, blends of blast-furnace slag powder, gypsum and calcium carbonate in blending ratios of 20:7:3, 20:5:5, 17:10:3, 15:10:5, 30:10:5 (weight basis), as described in Patent document 1.
Patent document 1: Japanese Unexamined Patent Application Laid-open No. H05-116996